Merge branch 'jm-zoekt-index-reserved-storage-watermark' into 'master'

Add storage watermark to zoekt indices

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/166222



Merged-by: Bishwa Hang Rai <bhrai@gitlab.com>
Approved-by: Bishwa Hang Rai <bhrai@gitlab.com>
Reviewed-by: Terri Chu <tchu@gitlab.com>
Reviewed-by: Bishwa Hang Rai <bhrai@gitlab.com>
Reviewed-by: Bojan Marjanovic <bmarjanovic@gitlab.com>
Co-authored-by: John Mason <jmason@gitlab.com>